Selector



July 20, 1954 w w, p s 2,684,407

SELECTOR Filed Oct. 28, 1952 2 Sheets-Sheet 2 Y'I\ Z-3 Z I\ 4 2-2 i Y j I ('4 (-H M RA HUNT ASSIST T o 0 o o o o o o o o o O o o o o o 0 o 0 o o o o o o o o o o o o o o o o o o o o 1 1% FIG 2 INVENTOR. I WILLIAM w. PHARIS BY: S2.

ATTORNEY Patented July 29, 1954 UNITED STATES "i TENT OFFICE SELECTOR William W. Pharis, Rochester, N. Y., assignor to Stromberg-Carlson Company, a corporation of New York 2 Claims.

The present invention relates to telephone systems and more particularly to an improved selector circuit for use with dial telephone systems.

Telephone exchanges adapted to be used with modern telephone systems employ considerable amounts of relatively complex equipment and circuits therefor. Many of these circuits are directively controlled for selective operation in response to dial impulses to thereby control the operation of switches for connecting the calling line to the desired called line. There are a number of principal types of individually selectable circuits for use to directively control switching mechanisms such as linefinder circuits, selector circuits, and connector circuits. In the case of a selector circuit, such circuit may normally have three principal conditions of operation, i. e., the free or idle condition ready for seizure by other circuits; seized by other circuits but not in the talking condition; or seized and in the talking condition. In monitoring the operation of the selector circuit and its associated switch mechanism it is desirable to be able to ascertain at a glance the principal operative condition of the circuit as mentioned above.

It is an important object of the present invention to provide an improved selector circuit having visual signal means to indicate its various principal conditions of operation.

A feature of the invention is the provision of a monitor signal lamp to be brightly illuminated when the selector circuit is seized by either preceding or succeeding circuits but not in the talking condition, and to be dimly illuminated when the selector circuit is in the talking condition, the arrangement being such that the lamp is not illuminated when the selector circuit is idle, thus conserving power.

Other objects, features, and the attending advantages of the invention will be apparent with reference to the following specification and drawings in which Figs. 1 and 2, with Fig. 2 placed to the right of Fig. 1, form a complete diagram of the selector circuit of the invention.

Referring to the drawings, the battery designa tions and are used. Hereinafter, the expression battery will indicate the negative terminal of the battery and the symbol will indicate the positive terminal of the battery, and it is to be understood that the positive terminal of the battery is also connected to ground so that the use of the word ground is indicative of a connection not only to ground but also to the positive terminal of the station battery. 7

The selector switch mechanism for use with the circuit of the invention is preferably of the step-by-step type and, for example, may be of the flat type in which the main set of switch wipers move in a single plane, the secondary being at right angles to the primary movement. The switch shown in the drawings comprises a main set of wipers including four wipers or brushes indicated as tip T, ring R, sleeve S, and hunt sleeve HS, respectively. In the present description of the invention, the hunt sleeve brush HS serves no useful purpose although its application to dial telephone systems for purposes of supervision, message rate metering and other similar signaling and control functions is known. The switch also includes a set of overflow switches OF, ofi-normal switches XON which are operated when the switch moves off-normal in the primary direction, and a second set of off-normal switches YON which operate when the switch takes its first step'in the secondary direction. The switch further includes primary and-secondary direction magnets X and Y, respectively, and a release magnet Z together with release magnet switch contacts ZIZ3.

Assuming that the previous switching equipment such as a linefinder and circuit has been extended to the tip, ring, and sleeve leads, T, R, and 5 respectively (Fig. l) a circuit is completed for operating the calling bridge relay I20 over a loop extendin from ground appearing on the normal contacts OF-I of the overflow switch pile up through normal contacts MI, winding IZBA, normal contacts III, tip lead T, calling loop, ring lead R, normal contacts I I2, and winding I20B to battery. In response to the operation of relay I20, the delay relay I30 and the X delay relay I40 are energized in parallel over circuits extending from ground appearing on the normal contacts Z-I of release magnet Z through operated contacts I2! and winding of relay Hill to battery and from ground through normal contacts Z-I, operated contacts I2I, normal contacts XON-I of the X off-normal pile up XON,

' and through winding I ItB to battery, respec tively.

The previously described operation of the calling bridge relay I20, upon seizure of the selector circuit by the preceding circuit, closes contacts I23 to energize and brightly illuminate the monitor signal lamp LIB directly from battery to ground. The brightly illuminated monitor lamp thus indicates that the selector circuit is seized but not in the talking condition since the switching relay III] is not yet operated.

The previously described operation of delay bridge relay 23.

m-inal.

relay I 30 efiects the application of ground to the back sleeve lead S through operated contacts KM and busy key BK. If it is desired to furnish dial tone from the selector circuit, the dial tone lead GDT, Fig. 2, is connected to the tip side of the line through conductor 3|, operated contacts I42, winding I20A of relay I20, and normal contacts Iii. With this arrangement the'dial tone is removed when X-delay relay I40 releases at the completion of the group of impulses of the first digit.

When the calling party dials the first digit, the loop applied to the calling bridge relay I20 is interrupted according to thenumber of impulses for the digit dialed and relay I20 thereby pulses. Upon each closure of normal contacts I22, ground by way of operated contacts I33 .is applied through normal contacts I22, operated contacts I34 and Hit, and the primary direction magnet X to battery, "resulting in the stepping of the selector switch inthe primary direction.

Referring back now to the initial energization of the stepping magnet X, the main set of. switch wipers T, R and S has been moved one step in the X direction. It is noted at this point that both delay relays I36 and M are provided with slow-to-release characteristics so thatboth of these relays hold operated over the group of dial pulses referred to above. When the-selector switch takes the first step in the X direction,- the X off-normal contact springs XON operate and thereby deenergize winding I403 at now-open contacts XONI but relay I40 holds operated until the last impulse has been received over a circuit extending from battery through winding MIlA, operated contacts I43 and I34, normal contacts I22, and operated contacts I33. Thus, relay l -l0 holds operated over the pulsing .:ground through the pulsing contacts I22 .ofvthe calling Relay I l-0 releases at-the end of the delay period following the .conclusionof the dialed digit at which time groundion operated contacts i3I of relay I30 (relay I30 remaining energized through operated contacts. I33 and now closed contacts I2 I) is conducted through normal contacts I44, operated oil-normal contacts XON- 2, conductor 32, normal contacts YON-I, of the Y off-normal springs, winding 2IOA of hunt relay 2m, normal-contactsv 2H and normal contacts 2-3 of the release magnetZto battery.

The foregoing circuit operates relay 2 I0 toclose a path operating the stepping magnet Y=-over a circuit extending from battery through-magnet Y, operated contacts 2I2, normalcont-acts H4, and operated contacts I3I toground. This'circuit energizes stepping magnet Y. andcauses .the selector switch to move one step in thesecondary or Y direction into the level of. the bank ofcontacts or terminals.

At this point it should be noted that upon the operation of hunt relay 2 i0, that relay is locked up from ground on operated contacts I3 I through normal contacts H3, operated contactsZIS, interrupter spring Y-l to winding- 2 I 0A. Thus, re-

lay ZIil is held operated until the stepping :mag-

net Y operates to open the interrupter springs Y--I.

As the switch advances in the Y direction, the sleeve or test wiper S" is employed to'make the usual busy test. Means (not shown) is provided for applying a desired potential, usually., round, upon the sleeve bank terminalsorcontacts in the sleeve banks to indicate a busy condition of the line or trunk terminating in-that contact or ter- If the first sleeve or testcontact .isrnot such relay.

.an idle line. test wipers encounters a busy contactand cireratecl'contacts XON2, conductor 32, operated contacts .YON-Lwinding of switching relay 5 I0,

normal contacts OF-Z of the overflow pile up OF, Y-interrupter YI, windings 2IOA and 2MB in series, and through release magnet switch contacts Z3 to battery. Switching relay I It operates from the resulting current flow over the abovedescribed pathbut relay 2 I 0 does not operate because that relay is not designed to operate on the. relatively low current now flowing.

Operation of relay III? extends he tip and ring leads T1 and R to the tip and ring brushes T and R, respectively, at the operated contacts I I5 and IE5, respectively,..and.the circuit for the calling bridgerelay. I20 is thereby broken totlius release With the switching relay IIll operated and the calling bridge relay iZt released, the selector. circuit. is now in what may be termed the seized andtalking condition, and contacts IiQA are closed while contacts I23 are open to thus.connect-theresistor RIO in series with the monitor-signal .lamp LIE? between battery and ground. -In such manner the monitor signal lamp i nowdimly illuminated to indicate the seized and talking: condition of the selector circuit.

The operation of switching relay I20 extends thesleeveleads to thesleeve or test wiper S at operated-contacts I I1. -With the circuit for maintaining the relay. I20 broken at contacts ii! and IE2, the resulting release of relay IZil deenergizes relay-I-illat nowiopen .contacts I2I after a time,- relay I30 .releases.

The .foregoing discussion related to the test brush S-encountering an idle sleeve contact for It may now be assumed that the cuit. as: indicatedby; presence of 1. ground. on the first sleeve test contact. Ground thereby ap- .pears 'onthe .sleevewiper .S' and is conducted through normal contacts I IIAand operated contacts I35 to winding of. relay H0.

Inasmuch as the other terminal ,of the winding of relay Iii is :connected to ground through off-normal springs YON-2, conductor 3.2, off-normal contacts.XON-2,.normal contacts. I lfi and operated contacts -I3I, relay IIIJ-is shunted down by the presence1of.gr0und.on both sides of the coil. Thereforathe switching relay I I0 cannot .op- -erate.

Thissleeve ground indicative of a busy condition .isalso-.conducted through overflow springs OF-2 and interrupter contacts Y-I to Winding-.ZIGA in order to reoperate the hunt relay 2I-0.

-Upon .the =reoperation of relay 2 I 0, stepping magnet-Y isagain operated from ground-by way of operated contacts 2 I2 so that-the Y magnet receivesanother pulse to advance the switch to the second position .in the level. .Inorder .to assure that the Y magnet will operate and that switchingrelay I I0 will remain shunted down until the next contact in. the level is reached, ground. on

repeated. If the outlet is idle, the selector is switched through but if the outlet is busy, the selector continues to hunt until an idle outlet is found. If all outlets are busy, the switch steps into the Y overflow position thereby operating the overflow pile up OF. Operation of the overflow springs is utilized to prevent further operation of relay 2 lil because of the opening of its operating circuit at contacts OF-2. Busy tone is forwarded from the busy tone lead BT through operated overflow contacts OF-3, normal contacts MI, winding [20A, normal contacts Hi, and tip lead '1 to the calling line or incoming trunk to thereby inform the calling party that all levels are busy.

Assuming that the succeeding circuit is seized, ground is returned on the front sleeve in any suitable manner by way of test wiper S through operated contacts H1, normal contacts I 14, operated contacts XON-Z, conductor 32, operated off-normal contacts YON-Z to switching relay winding H9 in order to hold relay H0 operated.

The circuit of Figs. 1 and 2 is released upon the removal of ground on the succeeding circuit as by hanging up by the called party. Release of relay H0 effects energization of release magnet Z from ground (not shown) on lead RA through normal contacts I36 and H9, operated contacts XON-il and YON-3 in parallel, through the release magnet Z to battery. At the same time, the restoration of the switching relay H0 opens contacts 9A to deenergize the monitor signal lamp LN) thus indicating that this circuit is idle. It should be pointed out that the selector switch circuit is normally in the idle condition for the greater part of the time and that the monitor signal lamp arrangement of the invention therefore operates with economy since the lamp is not illuminated for that greater portion of the time when the circuit is not in use. It will be understood that the condition of selector operation having the second greatest average period of use is when the selector circuit is seized and in the talking condition, i. e., switched through. At such time, the monitor signal lamp is dimly illuminated to conserve power.

While the monitor signal lamp arrangement of the invention has been described with a particular form of selector circuit, it should be understood that the signaling arrangement may be used with any form of selector circuit having at least a first relay to respond to the seizure of the circuit and a second relay to be operated when the selector circuit is switched through. Various modifications may be made within the spirit of the invention and the scope of the appended claims.

What I claim is:

1. A monitor signal lamp circuit to indicate the operative condition of a telephone selector circuit for selectably connecting a preceding circuit to a succeeding circuit, said switch circuit having incoming connections to said preceding circuit and outgoing connections to said succeeding circuit and switch means therebetween, said switch means when operated being effective to establish a circuit connection between said incoming connections and said outgoing connections, including in combination, a power source, a signal lamp, a resistance, circuit means responsive to the connection of said switch circuit to said preceding circuit to connect said lamp directly to said source of power, and circuit means responsive to the operation of said switch means and the consequent connection of said switch circuit to both preceding and succeeding circuits for connecting said lamp to said power source in series with said resistance.

2. A selector switch circuit for connecting a preceding circuit to a succeeding circuit in a telephone system and having a monitor signal lamp arrangement including in combination, a power source, a resistance, a signal lamp, a first relay adapted to be operated when said switch circuit is connected to said preceding circuit, a second relay adapted to be operated when said switch circuit is switched through to connect said preceding ciruit to said succeeding circut, circuit means including operated contacts of said first relay and normal contacts of said second relay to connect said signal lamp directly to said power source, and circuit means including normal contacts of said first relay and operated contacts of said second relay to connect said lamp in series with said resistance to said power source.

No references cited. 

